Why are some people not embarassed by standing outside in their yard, screaming at each other, or at their kids, at the top of their lungs?

They think everybody else is just like them, or wants to be.

Embarrassment implies a sense of shame, which, you may have noticed, few of these folks have.

^Shame would require a sense of self awareness, even empathy. More rare traits.

They simply don’t care about what anyone thinks, or how their own behavior affects other people. They do what they want/feel whenever they want/feel like doing it.

Ick.

They’re lowlifes.